The present invention generally relates generally to the field of automatic faucets. More particularly, the present invention relates to an improved capacitive touch controller for automatic faucets.
Automatic faucets have become popular for a variety of reasons. They save water, because water can be run only when needed. For example, with a conventional sink faucet, when a user washes their hands the user tends to turn on the water and let it run continuously, rather than turning the water on to wet their hands, turning it off to lather, then turning it back on to rinse. In public bathrooms the ability to shut off the water when the user has departed can both save water and help prevent-vandalism.
One early version of an automatic faucet was simply a spring-controlled faucet, which returned to the “off” position either immediately, or shortly after, the handle was released. The former were unsatisfactory because a user could only wash one hand at a time, while the latter proved to be mechanically unreliable.
One solution was the hands-free faucet. These faucets typically employ an IR or capacitive proximity detector and an electric power source to activate water flow without the need for a handle. Although hands-free faucets have many advantages, some people prefer to control the start and stop of water directly, depending on how they use the faucet. For example, if the user wishes to fill the basin with water to wash something, the hands-free faucet could be frustrating, since it would require the user to keep a hand continuously in the detection zone of the proximity sensors.
Thus, for many applications touch control is preferable to hands-free control. Touch control provides a useful supplement to manual control. Typically, faucets use the same manual handle (or handles) to turn the water flow off and on and to adjust the rate of flow and water temperature. Touch control therefore provides both a way to turn the water off an on with just a tap, as well as a way to do so without having to readjust the rate of flow and water temperature each time.
Since the purpose of a touch-control is to provide the simplest possible way for a user to activate and deactivate the flow of water, the location of the touch control is an important aspect of its utility. The easier and more accessible the touch control, the more effort is saved with each use, making it more likely that the user will take advantage of it, thereby reducing unnecessary water use. Since the spout of the faucet is closest to the position of the user's hands during most times while the sink is in use, the spout is an ideal location for the touch control. However, locating the capacitive touch sensor on the spout may cause inaccuracies due to the flow of highly conductive water through the spout. The handle of a faucet is another good location for a touch sensor, because the user naturally makes contact with the handle of the faucet during operation.
The present invention provides an improved capacitive touch sensor which is sensitive to a user's touch without being sensitive to resistive impedance due to water flowing adjacent an electrode of the sensor. Therefore, the capacitive touch sensor can detect a user's touch quickly while using minimal power.
According to one illustrated embodiment of the present invention, a fluid delivery apparatus comprises a spout, a fluid supply conduit supported by the spout, a valve assembly to supply fluid through the fluid supply conduit, a capacitive touch sensor including an electrode, and a pulse generator. The apparatus also includes a DC filter coupled to an output of the pulse generator and to the electrode, a rectifier having an input coupled to an output of the DC filter, and a controller coupled to an output of the rectifier. The controller is also coupled to the valve assembly. The controller is configured to detect a user touching the electrode based on an output signal from the rectifier and configured to control flow of fluid through the fluid supply conduit.
In one illustrated embodiment, a proximity sensor is located adjacent the spout. The proximity sensor is coupled to the controller to provide a hands free supply of fluid through the fluid supply conduit in response to detecting a user's presence with the proximity sensor. The controller switches back and forth between a manual mode and a hands free mode in response the capacitive touch sensor detecting the user touching the electrode.
In another illustrated embodiment, a handle is provided for manually controlling the valve assembly to provide fluid flow through the fluid supply conduit. The controller switches back and forth between a manual mode and an automatic mode in response to the capacitive touch sensor detecting the user touching the electrode.
It is understood that the capacitive sensing techniques described herein have applications other than just the fluid delivery devices illustrated herein. According to another illustrated embodiment of the present invention, a capacitive touch sensor comprises an electrode, a pulse generator, a DC filter coupled to the pulse generator and the electrode, a rectifier having an input coupled to an output of the DC filter, and a control circuit coupled to an output of the rectifier. The control circuit is configured to detect a user touching the electrode.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.